Stencil with pattern and method for forming pattern on workpiece

ABSTRACT

A stencil with pattern includes a porous material and a masking pattern layer disposed on the porous material. The masking pattern layer includes a patterned mask area covering a portion of the porous material. When electroplating or etching is performed, the stencil with pattern is laminated with a workpiece so that the patterned mask area covers a portion of a working surface of the workpiece, and is placed into an electroplating tank or etch tank. The portion of the working surface not covered by the patterned mask area undergoes electroplating or etching reaction, resulting in electroplated or etched pattern on the workpiece. There may also be a screen structure interposed between the porous material and the masking pattern layer. The method of forming a pattern on a workpiece using the stencil with pattern has advantages of simplified process, significant time-to-product reduction, and product yield enhancement.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stencil for electroplating and etching, and a method for forming an electroplated or etched pattern, and more particularly to a stencil with pattern and a method for forming a pattern on a workpiece using the stencil with pattern.

2. Description of the Prior Art

Electroplating and etching have various applications, such as finishing, forming etched pattern finish, manufacturing nameplates, manufacturing IC leadframes and circuits in circuit boards and so on. Currently, the electroplating and etching processes used by various industries are similar. FIG. 1 a to FIG. 1 e illustrate steps of an electroplating method for forming a pattern on a workpiece. As illustrated in FIG. 1 a, a photosensitive material 12 resistant to electroplating is coated or printed on a workpiece 10, or is disposed thereon through film lamination. Next, as illustrated in FIG. 1 b, an exposure procedure is performed with a mask 14 having a pattern, and is followed by a developing procedure as illustrated in FIG. 1 c, so as to expose a working surface 101 to be plated with an electroplating layer. Thereafter, as illustrated in FIG. 1 d, the workpiece 10 along with the patterned photosensitive material 12 are placed in an electroplating tank (not illustrated) and an electroplating procedure is conducted, whereby an electroplating layer 16 is formed on the exposed working surface 101. Finally, a stripping procedure is performed to clean the photosensitive material 12, and the patterned electroplating layer 16 has been formed on the workpiece 10 as illustrated in FIG. 1 e.

FIG. 2 a to FIG. 2 e illustrate steps of an etching method for forming a pattern on a workpiece. As illustrated in FIG. 2 a, a photosensitive material 12 resistant to etching is coated or printed on a workpiece 10, or is disposed thereon through film lamination. Next, as illustrated in FIG. 2 b, an exposure procedure is performed with a mask 14 having a pattern, and is followed by a developing procedure as illustrated in FIG. 2 c, so as to pattern the photosensitive material 12 such that portions of a working surface 101 not intended to be etched are covered. Thereafter, as illustrated in FIG. 2 d, the workpiece 10 along with the patterned photosensitive material 12 are placed in an etching tank (not illustrated) and an etching procedure is conducted whereby etched cavities are formed at the working surface 12 not covered by the photosensitive material 12. Finally, a stripping procedure is performed to clean the photosensitive material 12, and a specific cavity pattern 18 has formed on the workpiece 10, as illustrated in FIG. 2 e.

Regardless for the aforementioned electroplating or etching process, the process mainly undergoes printing or coating of the photosensitive material, exposure, developing, followed by electroplating or etching, and then stripping to clean the plating-resistant or etching-resistant photosensitive material. For these processes, each time a desired pattern or circuit has to be created, the pattern for stopping electroplating or etching to work thereon, though the same for each time, has to be formed by repeating coating of the photosensitive material, exposure, developing and stripping, etc, which are high temperature, high humidity, strong acid, strong base processes that are highly complex and involve massive consumption of water, electricity and various chemicals, and are therefore more harmful to the environment.

SUMMARY OF THE INVENTION

The present invention is directed to a stencil with pattern and a method for forming a pattern on a workpiece using the stencil with pattern. Advantages of the present invention may include simplification of a manufacturing process, significant reduction of time-to-production, product yield enhancement, cost reduction, saving of water, electricity and chemicals, and dramatic decrease in environmental impacts.

According to an embodiment, a stencil with pattern includes a screen structure including at least a layer of reticular structure and a frame structure disposed on a periphery of the reticular structure, the reticular structure including a first surface and an opposite second surface; a masking pattern layer connected to the first surface of the reticular structure, the masking pattern layer including a patterned mask area covering a portion of the reticular structure; and a porous material disposed on the second surface of the reticular structure, the porous material having pores allowing a reaction liquid to flow therethrough and to the area not covered by the patterned mask area.

According to another embodiment, a stencil with pattern includes a porous material having pores allowing a reaction liquid to flow therethrough; and a masking pattern layer connected to one side of the porous material and extending to the porous material, the masking pattern layer including a patterned mask area covering a portion of the porous material.

According to still another embodiment, a method for forming a pattern on a workpiece including providing a workpiece having a working surface; providing a stencil with pattern, the stencil with pattern including a porous material and a masking pattern layer disposed on the porous material, the masking pattern layer including a patterned mask area; disposing the stencil with pattern on the workpiece such that the patterned mask area covers a portion of the working surface; placing the workpiece and the stencil with pattern into a reaction tank, whereby a reaction liquid flows through the porous material and by the portion of the working surface not covered to the patterned mask area to undergo a chemical reaction; and removing the stencil with pattern.

The objective, technologies, features and advantages of the present invention will become more apparent from the following description in conjunction with the accompanying drawings, wherein certain embodiments of the present invention are set forth by way of illustration and examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a to FIG. 1 e illustrate steps of a prior art method for forming an electroplated pattern on a workpiece;

FIG. 2 a to FIG. 2 e illustrate steps of a prior art method for forming an etched pattern on a workpiece;

FIG. 3 is a schematic diagram illustrating the stencil with pattern according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating the stencil with pattern according to another embodiment of the present invention;

FIG. 5 is a flow chart illustrating the method for forming a pattern on a workpiece according to an embodiment of the present invention;

FIG. 6 a to FIG. 6 e are schematic sectional diagrams illustrating steps of the method for forming a pattern on a workpiece according to the first embodiment of the present invention;

FIG. 7 a to FIG. 7 e are schematic sectional diagrams illustrating steps of the method for forming a pattern on a workpiece according to the second embodiment of the present invention;

FIG. 8 a to FIG. 8 e are schematic sectional diagrams illustrating steps of the method for forming a pattern on a workpiece according to the third embodiment of the present invention;

FIG. 9 a to FIG. 9 e are schematic sectional diagrams illustrating steps of the method for forming a pattern on a workpiece according to the fourth embodiment of the present invention, which is for etch of a circuit pattern on a circuit board; and

FIG. 10 a to FIG. 10 g are schematic sectional diagrams illustrating steps of the method for forming a pattern on a workpiece according to the fifth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 3 is a schematic diagram illustrating a stencil with pattern according to an embodiment. As illustrated in FIG. 3, the stencil with pattern 20 includes a screen structure 22, a masking pattern layer 24 and a porous material 26 that constitute a three-layer structure. The screen structure 22 includes one or multiple layers of reticular structure 221 and is framed by a frame structure 222 around the periphery of the screen frame structure 22. The reticular structure 221 includes a first surface 223 and an opposite second surface 224. The masking pattern layer 24 is connected to the first surface 223 of the reticular structure 221. The masking pattern layer 24 includes a patterned mask area 241 covering a portion of the reticular structure 221, wherein the patterned mask area 241 is created by a utilizing machining, laser processing or chemical processing technique. In another embodiment, the masking pattern layer 24 is connected to the first surface 223 of the reticular structure 22 and extends to the second surface 224. The porous material 26 is disposed on the second surface 224 of the reticular structure 221. The porous material 26 has pores (not illustrated) that allows a reaction liquid (not illustrated) to flow freely therethough and to a patterned non-mask area 242 of the screen structure 221 not covered by the patterned mask area 241.

When applying the stencil with pattern 20 to an electroplating process or etching process, the stencil with pattern 20 is laminated to an about to be patterned workpiece (not illustrated) so that the patterned mask area 241 masks a portion of the workpiece. The workpiece along with the stencil with pattern 20 are placed in an electroplating tank or etch tank. The patterned non-mask area 242 of the reticular structure 221, not covered by the patterned mask area 241, allows the electroplating or etch liquid to pass through to undergo electroplating or etching reaction with the working surface exposed from the patterned mask area 241, whereby electroplated pattern or etched pattern is formed on the workpiece. The porous material 26 and the material of the masking pattern layer 24 may be selected such that they are resistant to electroplating liquid or etch liquid.

Continuing the above description, when chemical operations like electroplating or etching is conducted, the frame structure 22 provides a tension to the reticular structure 221 keeping the reticular structure 221 and the masking pattern layer 24 bound thereto even and precise in dimension, and preventing folding or shifting from happening during the operation. Furthermore, during the operation, the porous material 26 on the second surface 224 of the reticular structure 221 applies a pressure to the reticular structure 221, so that the reticular structure 221 pushes the masking pattern layer 24 to bind tightly with the workpiece, whereby particular areas on the workpiece are protected by covering, and electroplating or etching of a pattern or circuit may then be performed. The porous material 26 may be configured to be loosely or tightly bound with the reticular structure 26.

FIG. 4 is a schematic diagram illustrating a stencil with pattern according to another embodiment. As illustrated in FIG. 4, the stencil with pattern 20 includes a porous material 26 and a masking pattern layer 24 disposed on one side of the porous material 26 and extending to the porous material, which constitute a two-layer structure. The masking pattern layer 24 includes a patterned mask area 241 that is patterned to cover a portion of the porous material 26, wherein the patterned mask area 241 is formed by a utilizing machining, laser processing or chemical processing technique.

When applying the stencil with pattern 20 illustrated in

FIG. 4 to an electroplating or etching process, the patterned non-mask area 242 of the porous material 26 is not covered by the patterned mask area 241 thereby allowing the electroplating or etch liquid to pass through and to undergo an electroplating or etching reaction with a working surface of the workpiece (not illustrated) not covered by the patterned mask area 241, so as to form an electroplated or etched pattern on the workpiece.

Continuing the above description, when the surface topography of the workpiece is not uniform, the surface of the porous material 26 and the masking pattern layer 24 thereon may form a 3-dimensional structure with varying height matching with the surface topography of the workpiece, whereby the patterned mask area 241 of the masking pattern layer 24 is tightly bound to the surface of the workpiece when the stencil with pattern 20 is laminated with the workpiece.

In the present invention, the stencil with pattern 20 may adopt the two-layer design or the three-layer design according to the precision required by the dimension of the pattern on the workpiece. For products that can tolerate less precise pattern, the two-layer design may be used; for products that require more precise pattern, the three-layer design may be used. Whether using the two-layer or three-layer design, the stencil with pattern 20 can be re-used for manufacturing of workpieces intended to have the same patterns, and only lamination of the stencil with pattern 20 and the workpiece is required to prepare for electroplating or etching, thereby fixing the disadvantage of requiring repeating procedures involving high temperature, high humidity, strong acid, strong base such as coating of photosensitive material, exposure, developing and stripping in order to form the pattern for each workpiece. Compared to the traditional process, the present invention saves a lot of processing procedures, greatly reduces the time required for manufacturing, raises the product yield, and cuts the need for water, electricity and chemicals, and is therefore of great help to cost lowering and environmental protection. In addition, when accommodating continuous production needs for roll material, the stencil with pattern may also be formed into a cylindrical shape, and a product with high pattern precision may be manufactured by controlling the dimension of the masking pattern layer along tangents of the cylinder.

FIG. 5 is a flow chart illustrating the method forming a pattern on a workpiece according to an embodiment. As illustrated in the figure, a workpiece and a stencil with pattern is provided in step 30, wherein the workpiece has a working surface and the stencil with pattern may be the three-layer structure including the screen structure, masking pattern layer and porous material as illustrated in FIG. 3, or the two-layer structure including the masking pattern layer and porous material as illustrated in FIG. 4. Then the stencil with pattern is laminated on to the workpiece such that the patterned mask area of the masking pattern layer covers a portion of the working surface in step 32. Thereafter, the workpiece and the stencil with pattern are placed in a reaction tank, so that a reaction liquid in the reaction tank flows through the porous material to chemically react with the working surface not covered by the patterned mask area in step 34. Finally, after the chemical reaction has completed, the stencil with pattern is removed in step 36.

In an embodiment, the aforementioned reaction tank is an electroplating tank, the reaction liquid is an electroplating liquid and the chemical reaction involves forming an electroplated pattern on the portion of the working surface not covered by the patterned mask area. In another embodiment, the reaction tank is a chemical etch tank or an electrolytic etch tank, and the chemical reaction involves forming an etched pattern on the portion of the working surface not covered by the patterned mask area. Alternatively, the aforementioned lamination of the stencil with pattern and the workpiece may be performed in the electroplating tank or etch tank.

In order to facilitate understanding of the objectives, characteristics and advantages of the present invention, sectional diagrams below schematically illustrating 5 ways to apply the method for forming a pattern on a workpiece of the present invention.

FIG. 6 a to FIG. 6 e are sectional diagrams schematically illustrating the method for forming a pattern on a workpiece according to the first embodiment. First, as illustrated in FIG. 6 a, a two-layer stencil with pattern 20 is prepared. The two-layer stencil with pattern 20 includes a porous material 26 and a masking pattern layer 24. Next, as illustrated in FIG. 6 b, the stencil with pattern 20 is laminated with a workpiece 40 such that the patterned mask area 241 covers a portion of the working surface 401. Thereafter, the workpiece 40 and the stencil with pattern 20 are placed in an electroplating tank (not illustrated) for electroplating to be conducted. As illustrated in FIG. 6 c, an electroplated layer 42 is formed on the portion of the working surface 401 not covered by the patterned mask area 241.

Next, as illustrated in FIG. 6 d, the stencil with pattern 20 is separated from the workpiece 40 and the formation of the electroplated layer 42 pattern on the working surface 401 as illustrated in FIG. 6 e has been completed. The separated stencil with pattern 20 can be laminated with another workpiece 40, and the steps illustrated in FIG. 6 a to FIG. 6 d may be repeated to complete another electroplated layer 42 pattern shown in FIG. 6 e.

FIG. 7 a to FIG. 7 e are sectional diagrams schematically illustrating the method for forming a pattern on a workpiece according to the second embodiment. In this case, the method is applied to forming an etched pattern on specific areas of the workpiece. First, as illustrated in FIG. 7 a, a two-layer stencil with pattern 20 is prepared. The two-layer stencil with pattern 20 includes a porous material 26 and a masking pattern layer 24. Next, as illustrated in FIG. 7 b, the stencil with pattern 20 is laminated with a workpiece 40 such that the patterned mask area 241 covers a portion of the working surface 401. Thereafter, the workpiece 40 and the stencil with pattern 20 are placed in an etch tank (not illustrated) for etching to be conducted. As illustrated in FIG. 7 c, an etched cavity 44 is formed on the portion of the working surface 401 not covered by the patterned mask area 241. Next, as illustrated in FIG. 7 d, the stencil with pattern 20 is separated from the workpiece 40 and the formation of the etched cavity 44 pattern on the working surface 401 as illustrated in FIG. 7 e has been completed. The separated stencil with pattern 20 can be laminated with another workpiece 40, and the steps illustrated in FIG. 7 a to FIG. 7 d may be repeated to complete another etched cavity 44 pattern shown in FIG. 7 e.

FIG. 8 a to FIG. 8 e are sectional diagrams schematically illustrating the method for forming a pattern on a workpiece according to the third embodiment. This example illustrates electroplating of a second copper plating pattern of a circuit board. First, as illustrated in FIG. 8 a, a three-layer stencil with pattern 20 is prepared. The three-layer stencil with pattern 20 includes a screen structure 22, a masking pattern layer 24 and a porous material 26. Next, as illustrated in FIG. 8 b, the stencil with pattern 20 is laminated with a workpiece 40 such that the patterned mask area 241 covers a portion of the working surface 401. Thereafter, the workpiece 40 and the stencil with pattern 20 are placed in an electroplating tank (not illustrated) for electroplating to be conducted. As illustrated in FIG. 8 c, an electroplated layer 42 is formed on the portion of the working surface 401 not covered by the patterned mask area 241. Next, as illustrated in FIG. 8 d, the stencil with pattern 20 is separated from the workpiece 40 and the formation of the electroplated layer 42 pattern on the working surface 401 as illustrated in FIG. 8 e has been completed. The separated stencil with pattern 20 can be laminated with another workpiece 40, and the steps illustrated in FIG. 8 a to FIG. 8 d may be repeated to complete another electroplated layer 42 pattern shown in FIG. 8 e. Here, before the second copper plating is applied on the circuit board, procedures like drilling, electroless copper plating, first copper plating may have to be first completed; and after the second copper plating is completed, subsequent processing may be needed.

FIG. 9 a to FIG. 9 e are sectional diagrams schematically illustrating the method for forming a pattern on a workpiece according to the fourth embodiment. This example illustrates etching for a circuit pattern of a circuit board. First, as illustrated in FIG. 9 a, a three-layer stencil with pattern 20 is prepared. The three-layer stencil with pattern 20 includes a screen structure 22, a masking pattern layer 24 and a porous material 26. Next, as illustrated in FIG. 9 b, the stencil with pattern 20 is laminated with a workpiece 40 such that the patterned mask area 241 covers a portion of the working surface 401, wherein the workpiece 40 is a circuit board. Thereafter, the workpiece 40 and the stencil with pattern 20 are placed in an etch tank (not illustrated) for etching to be conducted. As illustrated in FIG. 9 c, an etched cavity 44 is formed on the portion of the working surface 401 not covered by the patterned mask area 241. Next, as illustrated in FIG. 9 e, the stencil with pattern 20 is separated from the workpiece 40 and the formation of the etched cavity 44 pattern on the working surface 401 as illustrated in FIG. 9 e has been completed. The separated stencil with pattern 20 can be laminated with another workpiece 40, and the steps illustrated in FIG. 9 a to FIG. 9 d may be repeated to complete another etched cavity 44 pattern shown in FIG. 9 e.

FIG. 10 a to FIG. 10 g are sectional diagrams schematically illustrating the method for forming a pattern on a workpiece according to the fifth embodiment. This example illustrates forming a circuit pattern of a circuit board using an indirect additive method. First, as illustrated in FIG. 10 a, a three-layer stencil with pattern 20 is prepared. The three-layer stencil with pattern 20 includes a screen structure 22, a masking pattern layer 24 and a porous material 26. Next, as illustrated in FIG. 10 b, the stencil with pattern 20 is laminated with a workpiece 40 such that the patterned mask area 241 covers a portion of the working surface 401. Thereafter, the workpiece 40 and the stencil with pattern 20 are placed in an electroplating tank (not illustrated) for electroplating to be conducted. As illustrated in FIG. 10 c, an electroplated layer 42 is formed on the portion of the working surface 401 not covered by the patterned mask area 241 as a metal circuit. Next, as illustrated in FIG. 10 d, the stencil with pattern 20 is separated from the workpiece 40 and the formation of the electroplated layer 42 pattern on the working surface 401 as illustrated in FIG. 10 e has been completed. Thereafter, as illustrated in FIG. 10 f, a dielectric material 46 is laminated with the workpiece 40, and the temperature is raised to above the glass transition temperature of the dielectric material 46, maintained for an appropriate amount of time and then lowered to below the glass transition temperature. Finally, the workpiece 40 is separated from the dielectric layer 46, and the electroplated layer 42 originally plated on the workpiece, i.e. the metal circuit, has been transferred onto the dielectric layer 46, as illustrated in FIG. 10 g, and a basic circuit board 50 is been manufactured. Then the workpiece 40 with the electroplated layer 42 transferred can be laminated with the separated stencil with pattern 20; the steps illustrated in FIG. 10 a to FIG. 10 d may be repeated to complete another electroplated layer 42 pattern shown in FIG. 10 e; and the steps illustrated in FIG. 10 f to FIG. 10 g may be repeated to manufacture another basic circuit board 50.

In the foregoing embodiments, only single-side processing has been illustrated as example. If double-side processing is desired, then two sets of stencil with pattern may be produced so as to cover both sides with the required stencils with pattern, which are then placed into an electroplating tank or etch tank for further processing.

The method for forming a pattern on a workpiece may replace the complex processes such as repetitively coating photosensitive material, exposure, developing, drying and stripping that involve high temperature, high humidity, strong acid and strong base treatments in the traditional process. In such way, a great deal of manufacturing procedures may be eliminated for a product in mass production, thereby significantly reducing the time-to-production, enhancing the product yield, and saving water, electricity and chemicals, which cuts down the cost and dramatically reduces environmental harms.

While the invention is susceptible to various modifications and alternative forms, a specific example thereof has been shown in the drawings and is herein described in detail. It should be understood, however, that the invention is not to be limited to the particular form disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims. 

1. A stencil with pattern comprising: a screen structure comprising at least a layer of reticular structure and a frame structure disposed on a periphery of the reticular structure, the reticular structure comprising a first surface and an opposite second surface; a masking pattern layer connected to the first surface of the reticular structure, the masking pattern layer comprising a patterned mask area covering a portion of the reticular structure; and a porous material disposed on the second surface of the reticular structure, the porous material having pores allowing a reaction liquid to flow therethrough and to the area not covered by the patterned mask area.
 2. The stencil with pattern according to claim 1, wherein the masking pattern layer is connected to the first surface and extends to the second surface of the reticular structure.
 3. The stencil with pattern according to claim 1, wherein the frame structure provides a tension to the reticular structure so as to keep the masking pattern layer even.
 4. The stencil with pattern according to claim 1, wherein the reaction liquid is an electroplating liquid or an etching liquid.
 5. The stencil with pattern according to claim 4, wherein the masking pattern layer comprises plating-resistant or etch-resistant material.
 6. The stencil with pattern according to claim 1, wherein the patterned mask area is formed by utilizing a machining, laser processing or chemical processing technique.
 7. A stencil with pattern comprising: a porous material having pores allowing a reaction liquid to flow therethrough; and a masking pattern layer connected to one side of the porous material and extending to the porous material, the masking pattern layer comprising a patterned mask area covering a portion of the porous material.
 8. The stencil with pattern according to claim 7, wherein the reaction liquid is an electroplating liquid or an etching liquid.
 9. The stencil with pattern according to claim 8, wherein the masking pattern layer comprises plating-resistant or etch-resistant material.
 10. The stencil with pattern according to claim 7, wherein the patterned mask area is formed by utilizing a machining, laser processing or chemical processing technique.
 11. A method for forming a pattern on a workpiece comprising: providing a workpiece having a working surface; providing a stencil with pattern, the stencil with pattern comprising a porous material and a masking pattern layer disposed on the porous material, the masking pattern layer comprising a patterned mask area; disposing the stencil with pattern on the workpiece such that the patterned mask area covers a portion of the working surface; placing the workpiece and the stencil with pattern into a reaction tank, whereby a reaction liquid flows through the porous material and to the portion of the working surface not covered by the patterned mask area to undergo a chemical reaction; and removing the stencil with pattern.
 12. The method for forming a pattern on a workpiece according to claim 11, wherein the reaction tank is an electroplating tank, the reaction liquid is an electroplating liquid, and the chemical reaction involves forming an electroplated pattern on the portion of the workpiece not covered by the patterned mask area.
 13. The method for forming a pattern on a workpiece according to claim 11, wherein the reaction tank is an etch tank, the reaction liquid is an etch liquid, and the chemical reaction involves creating an etched pattern on the portion of the working surface not covered by the patterned mask area.
 14. The method for forming a pattern on a workpiece according to claim 11, wherein the stencil with pattern further comprising a screen structure disposed between the porous material and the masking pattern layer.
 15. The method for forming a pattern on a workpiece according to claim 14, wherein the screen structure comprises at least a reticular structure and a frame structure disposed on a periphery of the reticular structure, the reticular structure is bound with the masking pattern layer, and the frame structure provides a tension to the reticular structure so as to keep the masking pattern layer even.
 16. The method for forming a pattern on a workpiece according to claim 11, wherein the masking pattern layer comprises plating-resistant or etch-resistant material. 